1. Field of the Invention
This invention relates to image processing technology, and more particularly, to a low-backlight image visibility enhancement method and system which is designed for use with a backlit-type of display unit, such as a TFT-LCD (Thin-Film Transistor Liquid Crystal Display) active matrix display unit, for visibility enhancement of the video images displayed on the display unit under a low-backlight condition.
2. Description of Related Art
TFT-LCD (Thin-Film Transistor Liquid Crystal Display) is a dot-matrix display technology widely utilized on various types of personal computers and portable electronic devices such as notebook computers and intelligent mobile phones. The TFT-LCD is equipped with an N×M dot matrix which is an array of N rows and M columns of pixels, wherein each pixel is capable of displaying a particular color or grayscale value in response to the charging of a particular level of data voltage thereto.
Fundamentally, the liquid crystal material used by TFT-LCD is incapable of light emitting, but it has a light transmittance that can be varied by the externally applied voltage; i.e., its light transmittance is nearly 100% when the externally applied voltage is zero, and nearly 0% when the externally applied voltage is at a certain maximum magnitude. Therefore, the externally applied voltage can be varied between zero and the maximum magnitude to render the LCD pixels to visually display specific grayscale levels. For this sake, TFT-LCD should be equipped with a backlighting module that can generate a backlight to illuminate the TFT-LCD dot-matrix screen during operation.
In the applications on notebook computers and mobile phones, since these portable devices are battery powered, the operation of TFT-LCD should be power efficient. However, since the backlighting module on TFT-LCD is used for light emitting, which is power consumptive, it will cause the battery to have a shortened life of use. One solution to this problem is to lower the backlight intensity. However, one drawback to this solution is that it would cause the displayed image to have a dimmed level of visibility to the user who might be unable to view the displayed image clearly.
In view of the aforementioned problem, it is a research effort in the computer industry for a new TFT-LCD technology that can use a lowered level of backlight while nonetheless allowing the displayed image to have a good level of visibility to the user.